A communication system can be seen as a facility that enables communication sessions between two or more entities such as user equipment and/or other nodes associated with the communication system. The communication may comprise, for example, voice, data, multimedia and so on. A user equipment may, for example, be provided with a two-way telephone call, multi-way conference call or a data communication session. A user equipment may also be provided with a connection to an application server (AS) which enables use of services provided by the application server.
A communication system typically operates in accordance with a given standard or specification which sets out what the various entities associated with the communication system are permitted to do and how that should be achieved. For example, the standard or specification may define if the user or, more precisely, user equipment is provided with a circuit switched service and/or a packet switched service. Communication protocols and/or parameters which shall be used for the connection may also be defined. In other words, a specific set of “rules” on which the communication can be based on needs to be defined to enable communication by means of the system.
Examples of communication systems may include fixed line communication systems, such as a public switched telephone network (PSTN), wireless communication systems, such as a public land mobile network (PLMN) and/or other communication networks, such as an Internet Protocol (IP) network and/or other packet switched data networks. Various communication systems may simultaneously be concerned in a connection.
The PSTN is a circuit switched communication system providing telephone call services, electronic mail (email) functionalities, facsimile services and so on for fixed line user equipment.
The PLMNs are typically based on cellular technology. In cellular systems, a base transceiver station (BTS) or similar access entity serves wireless user equipment (UE), such as mobile stations (MS), via a wireless interface between these entities. The communication on the wireless interface between the user equipment and the elements of the communication network can be based on an appropriate communication protocol. The operation of the base station apparatus and other apparatus required for the communication can be controlled by one or several control entities. The various control entities may be interconnected. One or more gateway nodes may also be provided for connecting the cellular network to other networks.
An example of the services that may be offered for users or subscribers by a communication system is the so called multimedia services. An example of the communication systems enabled to offer multimedia services is the Internet Protocol (IP) Multimedia network. IP Multimedia (IM) functionalities can be provided by means of an IP Multimedia Core Network (CN) subsystem, or briefly IP Multimedia subsystem (IMS). The IMS includes various network entities for the provision of the multimedia services.
The third generation partnership project (3GPP) has defined use of the general packet radio service (GPRS) as a backbone communication system for the provision of the IMS services. Therefore, the GPRS will be used in this specification as an example of a possible backbone communication system enabling the multimedia services. The 3G PP has also defined a reference architecture for the third generation (3G) core network which will provide the users of user equipment with access to the multimedia services. This core network is divided into three principal domains. These are the Circuit Switched (CS) domain, the Packet Switched (PS) domain and the Internet Protocol Multimedia Core Network Subsystem (IMS) domain. The last of these, the IMS domain, is for ensuring that multimedia services are adequately managed. The 3GPP IMS domain uses the Session Initiation Protocol (SIP) developed by the Internet Engineering Task Force (IETF) for creating, modifying and terminating sessions with one or more participants (endpoints).
It is expected that various types of services are to be provided to users by means of different Application Servers (AS) over IMS systems. User or several users related to the same subscriber may be able to use services simultaneously from different contact addresses, such as from different user equipment. In certain cases, the use of the same service by one user or several users related to the same subscriber from several contact addresses may cause capacity problems for example in charging the services. It might in certain cases be desirable to be able to provide different service classes depending on the subscriber or user. Furthermore, capability of controlling simultaneous registrations by a single user or several users related to the same subscriber might be useful for other reasons, such as fraud prevention.
These issues are not limited to 3GPP environments, but may occur in other communication systems as well. There is therefore a need for providing a way of controlling, such as counting or limiting, simultaneous registrations for services by a single subscriber or user in communication system providing services.